The “nano killer” enables efficient sterilization of anaerobic microorganisms

Schematic diagram of anaerobic sterilization mechanism of physical extraction and chemical oxidation Synergy Courtesy of the Ocean

Recently, the journal “Journal of Hazardous Materials”, an international magazine in the field of environmental science, published the latest research results of Zhang Dun’s research group at the Institute of Oceanography of the Chinese Academy of Sciences, and the research team found that the nano-killer activated by persulfate can achieve efficient sterilization of anaerobic microorganisms.

Based on the synergistic effect of physical damage and chemical oxidation of MoS2 (molybdenum disulfide) nanosheets, a fast and efficient sterilization system for anaerobic bacteria was constructed. The blade-like edges of the MoS2 nanosheet can be inserted into the cell membrane and lipids extracted. Due to the efficient electron transfer capacity of Mo (molybdenum) and the strong adsorption of persulfates and water by the S (sulfur) vacancy in MoS2, MoS2 can catalyze the production of SO4 and OH. These substances attack the lipids on the surface of MoS2 to achieve sterilization. Through the synergy of physical damage and chemical elimination, fast and stable sterilization in various environments can be achieved. This work will provide important reference value for expanding the mechanism of anaerobic sterilization.

Microbial fouling in the marine environment and microbial-induced corrosion is a serious economic and safety problem, China’s corrosion caused by economic losses accounted for about 3.34% of the GDP of that year, and marine corrosion losses accounted for about 1/3 of the total corrosion losses, more than 700 billion yuan, with the deterioration of the marine environment, economic losses may increase.

Among corrosive bacteria, Sulfate-Reducing Bacteria (SRB), which are widely distributed in hypoxic environments, have long been widely recognized as the culprits of corrosive failure of metal materials. Recently, materials with cytotoxicity have attracted widespread attention. MoS2 nanosheets are typical two-dimensional materials, due to the electrostatic effect between S and lipids and van der Waals force, showing significant cytotoxicity, the negative sulfur in MoS2 is easily bound to the hydrophilic head of lipids, so that the edges of MoS2 can be like a knife to cut through cell membranes, extract lipids, and eventually lead to cell death. Studies have shown that the S vacancies in MoS2 have a strong adsorption effect on permonosulfate (PMS) and water, which can catalyze the production of strong oxidizing free radicals. Therefore, using these two properties of MoS2, a new sterilization mechanism for anaerobic microorganisms can be proposed.

The study kills anaerobic microorganisms through the physical and chemical synergy of MoS2, as shown in the figure, for SRB and PA, with the assistance of PMS, the addition of low concentrations of MoS2 can achieve efficient sterilization rates. According to first-principles calculations, MoS2 adsorption PMS has a lower energy barrier than H2O, so PMS is more easily absorbed and excited than H2O on the Surface of MoS2. After MoS2 adsorbs H2O and PMS, it undergoes a series of intermediate changes to generate strongly oxidizing free radicals, which attack the lipids on the bacterial cell membrane, eventually leading to the death of the bacteria.

The research was supported by the National Natural Science Foundation of China, the Science High-end User Project and the 2018 Shandong Marine Science and Technology Project. (Source: China Science Daily Liao Yang, Li Hezhao Sirun)

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